Word Order
In my spanish workbook, there is an answer which I am supposed to write a question for. The answer is "Ella está leyendo su libro." My answer to that was "¿ Qué es ella haciendo?" But, the book answer was " Qué esta haciendo ella?" Why does the book say "esta" instead of "es" and why is the "ella" on the end instead of at the front where I had it?
8 Answers
Hi Melton, Echoline weighing in here....I can't find my old answer, either, but this might help. I think that you are having a difficulty with understanding the word "ser". In English, we lump everything about a person into one tiny verb, to be. But this is where Spanish has it all over us, as the language has taken good note of the fact that there are two parts of our "being". One is immutable...it is the "real" you, describing who you are as an individual. You would recognize a person by the words used to describe their "ser" (tall, short, honest, dishonest, loyal, trecherous).
Estar is for the stuff that comes and goes....what you're doing, where you are, etc.
Now, let's take a look at your sentence.
She is reading......
If you used "ser" (es), you would be saying that she literally IS the same thing as reading. She = reading. Well, that makes absolutely no sense at all, does it, and that's not at all how you menat it, either. See how that's different then what you use ser for? With ser, the equal sign makes sense she=tall, she=short, she=honest, etc. This was true yesterday and it will be true tomorrow and forward because that is what she truly "is".
What you are trying to communicate in this sentence is that she just happens to be reading her book at the moment. Ten minutes from now she'lll probably be doing something else, and another hour after that, something else again. All of these things that you "do" have to take the "estar" form.
Sometimes you just have to sit with a concept for a while before it sinks in. Ser vs. estar may just be one of those things for you. But when it does sink in, you will see how this concept can change how you see people...and situations. It can teach you that the ser of a person is what counts, and not the estar. It's really a lovely concept.
Oh okay then, let me explain you a little bit.
estar :
The apple is green. (Meaning the apple is not ripe.) = condition = La manzana está verde.
The apple is green. (Meaning the color of the apple is green.) = essential characteristics = La manzana es verde.
If you are talking about what something is, use ser; if you are talking about how something is, use estar.
And when talking about situations: I am reading, I am bored, I am here etc. = Estoy leyendo, Estoy aburrida, Estoy aquí.
Or while talking about the things that are permanent (at least those that can't be changed quickly) : This is my husband. : Esto es mi esposo. (but I'm married : estoy casada.) , He is boring! : ¡Es aburrido! ( but he is bored: está aburrido )
etc. etc. I hope this helps you a little bit more. 
The construction estar + gerundio (-ando, -iendo) is called a progressive verb tense, which implies an ongoing action, just like to be + (some verb)-ing in English. If estar is conjugated in the present tense (like your example) it's the present progressive. It just has to be estar, never ser. That's just the way they say it.
The reason ella is on the end in the question is because you normally reverse the word order for questions compared to statements.
¿Está leyendo ella? - Is she reading?
Ella está leyendo. - She is reading.
Usually you leave out the ella if it can be inferred from the context.
Thank you all! This really helps me out
A very basic explaination: Estar is used to describe the state of something and additionally it's used as an auxiliary verb with a gerund. Ser describes something, usually from inception, with no feeling involved.
Estoy triste....I am sad
Estoy comiendo........I am eating
Soy piloto........I am a pilot
Part two of your question...
in Spanish questions, the subject almost always comes after the verb.
Part one of your question...
to augment what you have already seen and heard, take a look at
great answer by Echoline ... trying to find link ..... sorry, this comes up so often her answer is buried but here are some links from dear Nametaken:
Please look here and here for more information about the difference between ser and estar. Also, please do a search as this question has been asked and answered many times before and you will find some brilliant answers.
I did go through some of that, but I still don't understand why. 
Hey , again you need to have a look at the lesson : ser vs. estar 
